Gravity-improved metastability bounds for the Type-I seesaw mechanism
Abstract Right-handed neutrinos (RHN) destabilize the electroweak vacuum by increasing its decay rate. In the SM, the latter is dominated by physics at the RG scale at which λ reaches its minimum,...
| Main Authors: | , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
Springer Berlin Heidelberg
2023
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| Online Access: | https://hdl.handle.net/1721.1/152383 |
| _version_ | 1826206167795236864 |
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| author | Chauhan, Garv Steingasser, Thomas |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Chauhan, Garv Steingasser, Thomas |
| author_sort | Chauhan, Garv |
| collection | MIT |
| description | Abstract
Right-handed neutrinos (RHN) destabilize the electroweak vacuum by increasing its decay rate. In the SM, the latter is dominated by physics at the RG scale at which λ reaches its minimum,
μ
∗
SM
$$ {\mu}_{\ast}^{\textrm{SM}} $$
∼ 1017 GeV. For large neutrino Yukawa coupling Yν, RHNs can push μ* beyond the Planck scale, implying that gravitational effects need to be taken into account. In this work, we perform the first comprehensive study of electroweak vacuum metastability in the type-I seesaw mechanism including these effects. Our analysis covers both low- and high-scale seesaw models, with two as well as three RHNs and for multiple values of the Higgs’ non-minimal coupling to gravity. We find that gravitational effects can significantly stabilize the vacuum, leading to weaker metastability bounds. We show that metastability sets the strongest bounds for low-scale seesaws with MN > 1 TeV. For high-scale seesaws, we find upper bounds on the allowed masses for the RHNs, which are relevant for high-scale leptogenesis. We also point out that Tr(
Y
ν
†
$$ {Y}_{\nu}^{\dagger } $$
Yν), which is commonly used to express these metastability bounds, cannot be used for all of parameter space. Instead, we argue that bounds can always be expressed reliably through Tr(
Y
ν
†
$$ {Y}_{\nu}^{\dagger } $$
Yν
Y
ν
†
$$ {Y}_{\nu}^{\dagger } $$
Yν). Lastly, we use this insight to develop a new technique for an easier RG analysis applicable to scenarios with degenerate RHN masses. |
| first_indexed | 2024-09-23T13:25:09Z |
| format | Article |
| id | mit-1721.1/152383 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T13:25:09Z |
| publishDate | 2023 |
| publisher | Springer Berlin Heidelberg |
| record_format | dspace |
| spelling | mit-1721.1/1523832024-01-31T21:35:42Z Gravity-improved metastability bounds for the Type-I seesaw mechanism Chauhan, Garv Steingasser, Thomas Massachusetts Institute of Technology. Department of Physics Abstract Right-handed neutrinos (RHN) destabilize the electroweak vacuum by increasing its decay rate. In the SM, the latter is dominated by physics at the RG scale at which λ reaches its minimum, μ ∗ SM $$ {\mu}_{\ast}^{\textrm{SM}} $$ ∼ 1017 GeV. For large neutrino Yukawa coupling Yν, RHNs can push μ* beyond the Planck scale, implying that gravitational effects need to be taken into account. In this work, we perform the first comprehensive study of electroweak vacuum metastability in the type-I seesaw mechanism including these effects. Our analysis covers both low- and high-scale seesaw models, with two as well as three RHNs and for multiple values of the Higgs’ non-minimal coupling to gravity. We find that gravitational effects can significantly stabilize the vacuum, leading to weaker metastability bounds. We show that metastability sets the strongest bounds for low-scale seesaws with MN > 1 TeV. For high-scale seesaws, we find upper bounds on the allowed masses for the RHNs, which are relevant for high-scale leptogenesis. We also point out that Tr( Y ν † $$ {Y}_{\nu}^{\dagger } $$ Yν), which is commonly used to express these metastability bounds, cannot be used for all of parameter space. Instead, we argue that bounds can always be expressed reliably through Tr( Y ν † $$ {Y}_{\nu}^{\dagger } $$ Yν Y ν † $$ {Y}_{\nu}^{\dagger } $$ Yν). Lastly, we use this insight to develop a new technique for an easier RG analysis applicable to scenarios with degenerate RHN masses. 2023-10-05T20:41:39Z 2023-10-05T20:41:39Z 2023-09-22 2023-09-24T03:14:24Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/152383 Journal of High Energy Physics. 2023 Sep 22;2023(9):151 PUBLISHER_CC en https://doi.org/10.1007/JHEP09(2023)151 Creative Commons Attribution http://creativecommons.org/licenses/by-nc-sa/4.0/ The Author(s) application/pdf Springer Berlin Heidelberg Springer Berlin Heidelberg |
| spellingShingle | Chauhan, Garv Steingasser, Thomas Gravity-improved metastability bounds for the Type-I seesaw mechanism |
| title | Gravity-improved metastability bounds for the Type-I seesaw mechanism |
| title_full | Gravity-improved metastability bounds for the Type-I seesaw mechanism |
| title_fullStr | Gravity-improved metastability bounds for the Type-I seesaw mechanism |
| title_full_unstemmed | Gravity-improved metastability bounds for the Type-I seesaw mechanism |
| title_short | Gravity-improved metastability bounds for the Type-I seesaw mechanism |
| title_sort | gravity improved metastability bounds for the type i seesaw mechanism |
| url | https://hdl.handle.net/1721.1/152383 |
| work_keys_str_mv | AT chauhangarv gravityimprovedmetastabilityboundsforthetypeiseesawmechanism AT steingasserthomas gravityimprovedmetastabilityboundsforthetypeiseesawmechanism |